Expansible pulley.



TTED STATES PATENT OEEICE.

EIVALD HERMSDORF, OF BRUNSWICK, GERMANY.

EXPANSIBLE` PU LLEY.

SPECIFICATION forming part of Letters Patent No. 688,173, dated December 3, 1901. Application tiled August 31,1901. Serial No. 74,012. (No model.)

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Beit known that I, EWALD HEEMSDORE, engineer, a subject of the King of Saxony, residing at Brunswick, Duchy of Brunswick, Germany, have invented certain new and useful Improvements in Adjustable Driving-Pulleys, of which the following is a specification.

My invention relates to improvements in driving-pulleys having a variable diameter for driving by means of a belt, rope, cord, or chain, in which alterations in the tension of the belt or the proportions of transmission are produced by alteration of the eiective diameter of the pulley. The alteration of the diameter of the pulley is rendered possible in the usual manner by forming the pulley of two side plates or disks which are connected by bars parallel to one another and one of which disks is firmly and the other loosely' mountedon the shaft. The bars form the periphery of the driving-pulley and are ilexibly attached to the plates in such a Way that their minimum distance from the axis of rotation of the pulley varies when one plate is turned relative to the other when the bars inelose the well-known form of a hyperboloid. For practical use-for instance, in obtaining a variable transmission-in these known driving-pulleys a great drawback is found in the circumstance that when the plate in question is turned with the object of altering the diameter the distance apart of the plates'is also altered-z'. e., the loose disk approaches or moves away from the fixed disk. As the place of strongest friction-4'. e., that on which the rope or like transmission organ runs-always lies in the center between the two disks of the pulley, at each adjustment or alteration of the diameter of the pulley a displacement of the running-place takes place, which causes asa consequence a deleterious distortion of the belt or the like.

My invention has for its object a drivingpulley of the kind hereinbefore mentioned, but in which such displacements do not take place.

In order to allow of the invention being better understood, a gearing formed of two driving-pulleys of the improved kind is shown in the accompanying drawing,the left-hand pulley being in section in the direction of its axis, while the right-hand one is in elevation.

A plate Z9, in which a large number of bars c are pivotally mounted in a ring, is suitably iixed on a shaft a. At a certain distance from the fixed plate b a second plate b' is revolubly mounted on the shaft a and is provided with a number of perforations d, corresponding to the bars c in such a Way that the latter can move in the holes d. This arrangement ot' driving -pulley allows of an alteration of its diameter by a mere rotation of the plate b-z`. e., without an alteration in the distance between the two plates as the bars adjust themselves-bylongitudinal displacement in the holes d to the length between the plate Z) and b actually necessary at any time. As the distance between both plates thus does not alter, the running-place of the belt e remains always in the same plane, so that distortions and excessive strains of the belt do not arrive.

In order that the bars c may not jam inthe holes CZ when the plates b are turned, the holes are well rounded or taperingly enlarged toward both sides of the plate. They may also be provided with ball-cups, which allows a substantially universal movement of the bars under secure guidance.

The rotation and iixing of the plates b may be elected by various means. In the example of construction shown in the drawing the following arrangement is employed: The hubf of the plate D' is made in the form of a socket, and in it a sleeve g is located,which is adjustable on the shaft a, but is prevented from revolving on the same and is provided with a spiral groove 7i, in which a stud t, formed on the interior of the hubsocket f, engages. If the sleeve be displaced in a straight line on the shaft d, its groove h by means of the studt' forces the plate b to rotate on the shaft, thus producing the desired alterations in the diameter of the pulley.

Of course instead of the groove 7L a rib or ridge running in a similar direction may also be arranged on the sleeve g, and in the hub f instead of the stud i a recess may be formed eter, the Combination with a shaft, of a platesuitably iixed thereon, a plate rovol'ubly mounted on the said shaft, and bars parallel to one another and pivotally connected with one plate and projecting through and freely movable in the other of said plates, whereby the alteration of the effective diameter of the pulley may be elected by turning the loose plate without altering the position of the running-surface of the belt or thelike on the pulley, substantially as described.

2. In an adjustable belt-pulley, the combination with a shaft, of a plate suitably fixed thereon, a plate revoluble on said shaft, bars parallel to one another and pivotally connected to one plate and projecting through and freely movable in the other of said plates, a sleeve arranged on the hub of the loose plate and displaceable on the shaft, and a guideon said sleeve for effecting the turning of the revoluble plate in suitable relation to the liixed plate.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

EVVALD HERMSDORF.

Witnesses:

J. SECKEL, A. WILLERD. 

